post-mortem changes time of death. post-mortem changes livor mortis/ hypostasis rigor mortis ...
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Post-Mortem Changes
Livor Mortis/ Hypostasis
Rigor Mortis
Algor Mortis/ Body Cooling
Decomposition Five general stages are used to describe the process
of decomposition in vertebrate animals: Fresh, Bloat, Active and Advanced Decay, and Dry/Remains
The general stages of decomposition are coupled with two stages of chemical decomposition: autolysis and putrefaction
Fresh Stage Begins immediately after death
Heart has stopped beating
Blood drains to dependent areas of body due to gravity
Creating a bluish-purple discoloration = livor mortis
Also known as lividity
Rigor Mortis occurs in this stage along with Algor Mortis
Autolysis starts due to cellular breakdown and changes in pH
Indications of Death Indications of death:
Unconsciousness Loss of all reflexes No reaction to painful stimuli Muscular flaccidity Cessation of heart beat and respiratory movement Eye signs:
Loss of corneal and light reflexes Mid-dilated position of the pupils Irregular size and shape of the pupils Eyelids usually closed incompletely Tache noire: where the sclera remains exposed, two triangles
of
discoloration appear at each side of the cornea, either brown or
black.
Postmortem Ocular Changes
Immediate signs in eyes Dilated or fixed pupils
Absence of corneal and light reflex
Marked decrease in intra-ocular pressure
Late signs in eyes Cloudiness of cornea
Increase in potassium levels
Early Postmortem Ocular Changes
Eyes remain open Thin film observed over
cornea within minutes Taché noire
Eyes closed upon death Cloudiness within twenty-
four hours
Absence of intraocular fluid suggests more than 4 days.
Time Since Death Interval
What Time Did the Person Die? Best estimate; offered with a reasonable
degree of medical and scientific certainty.
Impossible to be 100% accurate.
UNLESS a witness (who doesn’t lie) is present at the time of death, it generally is an estimate of time (2-4 hour window is the usual).
Terminology Postmortem Lividity: Physiochemical
changes of the Body after Death Livor Mortis: Discoloration after Death
Rigor Mortis: Stiffness after Death
Algor Mortis: Body temperature after Death
Time of Death To Evaluate Time Since Death:
Livor Mortis Rigor Mortis Body Temperature Stages of Decomposition Potassium Concentration in Vitreous Humor Stomach Contents Insect Activity Scene Markers Or a witness who can verify time of death
What is the Forensic Significance of Hypostasis?
Hypostasis is another term for Livor Mortis
Helps in determining Time of death
Position of the body after death
Cause of death from color
Hypostasis (Postmortem Lividity)
Livor mortis is the settling of blood.
When the heart stops, the blood stops circulating and gravity makes it settle. The areas where the blood has settled will turn pink to dark red to dark blue or purple.
Starts happening immediately and is visible within a couple of hours. At this point skin is pinkish/bluish and blotchy.
After five or six hours the blotches have joined up but the skin still goes white when pressed.
After ten to twelve hours the blue color remains even when pressed. The lividity doesn't show where the body is in contact with something.
Thus a body lying on its back will show lividity in the small of its back, its neck etc., but not parts of the body directly touching the ground.
This a very useful when determining if a body has been moved after death.
Livor Mortis Postmortem Lividity
Early stages can “Blanch” the skin
Can shift position(s) from 1-8 hours
8-12 hours congeals in capillary beds
After 12 -24 hours the lividity is typically “fixed”
Can continue to move up to 3 days after death
Blanching
Thumb pressure indicates that the lividity is not fully fixed.
Distribution of Hypostasis
If the body remains vertical after death as in hanging cases, hypostasis will be most marked
in the feet and to a lesser extent the hands.
Livor Mortis Noticeable approximately 30 minutes to 2
hours after death. Reddish purple coloration in dependent areas
of the body.
Due to accumulation of blood secondary to gravity.
Dependent areas resting on a hard surface may appear pale in color.
Sites of Hypostasis Depends on the position of the body before death:
Supine: shoulders, buttocks heels pressing against surface gives white color (pale).
Vertical (hanging): distally in legs & feet.
Drowning: chest, upper chest, and upper limbs.
Face-down death: as in epilepsy, drunken victims whitening around nose & lips.
Hypostasis may also occur in viscera: Heart: mistaken for MI Lungs: mistaken for pneumonia Intestine: mistaken for hemorrhagic infarction
Postmortem Changes Postmortem changes are affected by:
Victim’s Age
Victim’s Pre-morbid Health
Level of Activity at time of death
Type of drugs taken prior to death
Ingestion of drugs prior to death
Current Environmental conditions
Can you see hypostasis in the internal organs?
Yes
The lung is dark purple in the posterior dependent areas as a result of livor mortis. This may simulate congestion.
Cause of Death Analyzed by Livor Mortis
Etiology Color of Liver Mechanism
Normal Red-Blue-Purple Venous Blood
Carbon Monoxide Pink, cherry-red Carboxyhemoglobin
Cyanide Pink, cherry-red Excessive oxygenated blood because of inhibition of cytochrome oxidase
Refrigeration/hypothermia
Pink, cherry-red Oxygen retention in cutaneous blood by cold air
Hydrogen sulfate Green Sulfhemoglobin
Sodium chlorate Brown Methemoglobin
Hypostasis vs. Bruises (Ecchymosis)
Hypostasis BruisesDependant areas Any where
Well defined edges Ill defined edgesBlood is retained in intact capillaries
Blood escapes through ruptured capillaries
Superficial Deep into skinSame level on surface RaisedPale over pressure areas
Red
Incision: blood flows from the cut vessel (washable)
Incision: blood coagulates in tissue
No swelling May be with swelling With a bruise, blood will not flow
from the cut
Hypostasis In advanced stages, skin level capillaries can
hemorrhage This causes pinpoint breaks in the skin called
“Tardieu Spots” or petechiae.
Can see petechiae on internal organs.
These are minute hemorrhages in the soft tissue.
Scars show no lividity
Purpura = patches of purplish discoloration due to rupture of small vessels.
Tardieu Spots Tardieu spots are
petechiae and purpuric hemorrhages that develop in areas of dependency secondary to the rupture of degenerating vessels under the influence of increased pressure from gravity
Postmortem Rigor Mortis
Rigor Mortis Chemical changes
causes muscle mass to become rigid; looks like body is frozen in place (fixed)
Small muscles go into rigor first
Rigor usually occurs from head to toe Rigor = Rigid Mortis = Death
Rigor Mortis Formation
Mechanisms Leading to Rigor: Metabolic activity after death continues for
short time and becomes anaerobic (lacking oxygen)
ATP hydrolyzes to ADP
Calcium ions diffuse from sarcoplasmic reticulum
Causes chemical lock between actin and myosin proteins, THEN
As body proteins decompose, chemical locks breakdown and muscles become flaccid again.
Time table for Rigor Mortis
Rigor can be seen within 30 min. to 1 hour after death.
Covers the entire body after 8-12 hours. Complete Rigor will remain for about 8-12 hrs. Rigor begins to dissipate over the next 12 hrs.
This is dependent on environmental temperatures Fully flaccid body by 36 hours.
Cadaveric Spasm Drowning Great Excitement prior to death
Rigor Mortis Rigor is accelerated by
Prior exercise Convulsions Electrocution Hyperpyrexia Hot environmental temperatures Age (does not form well in children) Strychnine poisoning
Rigor is inhibited by Hypothermia Cold environment
Factors affecting timing of RM
Environmental temperature:
Cold and wet onset slow, duration longer
Hot and dry onset fast, duration shorter
Muscular activity before death:
Muscles healthy and robust, at rest before death slow onset, duration longer
Muscles exhausted/ fatigued onset rapid, esp in those limbs being used (eg in someone running at time of death, lower limbs develop RM faster than upper limbs)
Increase activity (convulsions, electrocution, lightning) rapid onset & short duration
Factors affecting timing of RM
Age:
Extremes of age rapid onset
Health:
Cause of death:
Asphyxia, pneumonia, nervous de’s with muscle paralysis & dehydration slow onset
Septicemia & poisoning rapid onset, may even be absent, especially in limbs affected by septicemia
Emaciated or died of wasting disease rapid onset, short duration
RM: time estimation
Warm Flaccid Death < 3 hrs
Warm Stiff 3-8 hrs
Cold Stiff 8-36 hrs
Cold Flaccid Death > 36 hrs
What is the Forensic Significance of Rigor Mortis?
Can tell Time of Death
Can tell whether the body has been moved
May be able to tell cause of death
Cadaveric Spasm Known as instantaneous rigor, cataleptic
rigidity, or instantaneous rigidity
Rare form of muscular stiffening that occurs at the moment of death, persists into the period of rigor mortis and can be mistaken for rigor mortis
The cause is unknown, but usually associated with violent deaths happening with intense emotion
Occurs in deaths Of Drowning
That occur with great excitement of tension
Rigor Mortis vs. Cadaveric Spasm
Rigor mortis Cadaveric spasm
Onset delayed after death (2-3 hrs)Duration approx 12-24 hrs
Onset is instantaneousDuration is a few hours, until it is
replaced by rigor mortis
Intensity comparatively moderate Intensity comparatively very strong
Mechanism of formation: breakdown of ATP below critical level
Mechanism of formation unknown, but predisposing factors: Excitement, fear, fatigue, exhaustion, nervous tension,
contraction of muscles at time of deathAll muscles of the body are affected
gradually.Selected muscles, which were in a state of contraction at the time of death, are
affected.
What is the Forensic Significance of Cadaveric Spasm?
Diagnosis of suicide as in case of weapon found in hand
Drowning Diagnosis
ID of assailant as in case of evidence in hand
May allow one to know state of person prior to death Stress
Exercise
Algor Mortis Algor Mortis (Body Cooling)
Body cools from normal internal temperature to the temperature in the environment. Liver or brain temperatures are taken for core
temperature
Body cooling is inaccurate in obtaining time of death.
In 70 – 75°F, the body cools 2.5°F to 2.0°F for first hour, then 1.5 to 2.0°F for next twelve hours, then 1.0°F for next 12 hours.
Time since death = 98.6°F – Rectal Temp (°F)/ 1.5 The rectum should be checked before insertion of the
thermometer (May have been a sexual assault)
Patient may not die immediately after assault. This may change time of death by several hours.
Algor Mortis Under average conditions the body cools
2.0°F to 2.5°F per hour during the first hours and slower thereafter with an average loss of 1.5°F to 2°F during the first 12 hours and 1F for the next twelve to eighteen hours.
Measure inner core temperature Liver or brain
Factors affecting Rate of Cooling
Body weight: Larger bw: slower cooling Smaller bw: faster cooling
Edema: slower cooling rate.
Surface area of the body: Larger surface area speeds up cooling rate. Children: increase surface area gives rapid heat
loss.
Factors affecting Rate of Cooling
Clothing, posture and emaciation
Environmental Temperature: Higher humidity: rapid cooling rate Rapid air velocity: rapid cooling rate
Water: Rapid cooling rate: More rapid in flowing water than still water
If there is a fulminating infection, e.g. septicemia, the body temperature may continue to rise for some hours after death.
Decomposition The decomposition of a body can be divided into several stages,
even if the duration of each stage will vary a lot:
2 - 3 days: green staining begins on the right side of the abdomen. Body begins to swell.
3 - 4 days: staining spreads. Veins go "marbled" - a browny black discoloration
5-6 days: abdomen swells with gas. Skin blisters
2 weeks: abdomen very tight and swollen.
3 weeks: tissue softens. Organs and cavities bursting. Nails fall off
4 weeks: soft tissues begin to liquefy. Face becoming unrecognizable
4 - 6 months: formation of adipocere, if in damp place. This is when the fat goes all hard and waxy.
A body without a coffin will be decayed within 12 years.
Putrefaction
The normal final sign of death.
Starts immediately after death at the cellular level
Becomes visible in 48-72 hrs.
Its onset may be sped up or delayed by several factors mainly: Temperature Humidity
Two phenomena for putrefaction: Autolysis: occurs by digestive enzymes released from the cells
after death. Bacterial action: most of them come from the bowel and
Clostridium welchii predominates (same bacteria that causes gas gangrene)
The 1st visible sign of putrefaction is green or greenish red
discoloration of the skin of the anterior abdominal wall Normally starts in the right iliac fossa.
The Next phase: Gas formation Blisters containing red fluid appear on the skin, mistaken
as bleeding
Humidity, temperature, bacterial activity body proteins break into
polypeptides & amino acids
Brain & Epithelial tissues are the 1st to be affected by putrefaction
Heart, Uterus & Prostate may survive for longer periods.
Military Plaques: nodules in heart (epi/endocardial)
Marbling: bacteria colonize venous system hemolysis stain.
PutrefactionThree Stages of Body Breakdown
Early Stage: 24-36 hours Green-like discoloration, usually in abdomen
(R-low) due to denaturation of bacteria in the colon
Putrefaction Middle Stage: 36-48 hours
Gaseous bloating, green-purple color in face, neck and shoulders.
Bloat First sign that microbial proliferation is
occurring
Accumulation of gases in body cavities causes distention of the abdomen
Insects feed on the body’s tissues Post-mortem skin ruptures
Allows gases and fluids to escape = Purging
Putrefaction Late Stage: greater than 72
hoursBloatingPostmortem mucosal purge,
tongue swells and protrudes, venous marbling of subcutaneous vessels
Skin blebs or blisteringExplosion of this person can occur
PutrefactionLate Stage (Cont.): greater than 72
hours
Skin and hair slippage skin of hands or feet can shed with nails
intact
Marked bloating (1-3X)
Skeletonization (from 4-5 days and up to 1.5 years depending on the climate).
Active Decay Greatest period of mass loss
Voracious feeding of maggots
Purging of decomposition fluids
Liquefaction of tissue and disintegration
This stage ends when maggots migrate from the body to pupate
Influences on Putrefaction A high environmental humidity will enhance putrefaction.
The rate of putrefaction is influenced by the bodily habits of the
decedent; obese individuals putrefy more rapidly than those who are
lean.
Putrefaction will be delayed in deaths from
exsanguination (bleeding to death) because blood provides a channel
for the spread of putrefactive organisms within the body. Conversely, putrefaction is more rapid in persons dying with widespread infection, congestive cardiac failure or retention of sodium and salts.
It tends to be more rapid in children than in adults, but the onset is
relatively slow in unfed new-born infants because of the lack of
commensal bacteria.
Influences on Putrefaction
Heavy clothing and other coverings, by retaining body heat, will speed up putrefaction.
Rapid putrefactive changes may been seen in corpses left in a room which is well heated, or in a bed with an electric blanket.
Injuries to the body surface promote putrefaction by providing portals of entry for bacteria and the associated blood provides an excellent medium for bacterial growth.
Timeline of Putrefaction
2–3 days: Discoloration appears on the skin of the abdomen. The abdomen begins to swell due to gas formation.
3–4 days: The discoloration spreads and discolored veins become visible.
5–6 days: The abdomen swells noticeably and the skin blisters.
2 weeks: The abdomen is bloated; internal gas pressure nears maximum capacity.
3 weeks: Tissues have softened. Organs and cavities are bursting. The nails fall off.
4 weeks: Soft tissues begin to liquefy and the face becomes unrecognizable.
The exact rate of putrefaction is dependent upon many factors such as weather, exposure and location
Case Study A 74-year old white male adult was found
dead in his one room apartment.
When police arrived they found him face down sprawled across his bed.
The room was approximately 75°F.
There were no apparent injuries to this individual.
Police concluded the death was natural and did not called the Coroner’s office.
Do you agree with their conclusion?
Why or why not?
Write down your answer and give a full explanation why you think the police were either correct or wrong. Make sure to use terminology presented in this
power point presentation.